Generally described, conventional dynamoelectric machines have forged rotors of a magnetic material with radial slots formed therein. The slots are used for the connective turns of a number of field windings. The field windings are interconnected so as to produce a desired magnetic flux pattern.
Rotors generally have a cylindrical rotor body with a shaft extending towards the generator. A locking key or a similar element may be positioned at the turbine/generator coupling. This key resists the excess torque that may be generated during an in service fault condition. In such a condition, excess torque may be generated on the rotor shaft.
As the generators have aged, fretting and cracking have been experienced in the keyway, in the rotor, and in the inside diameter of the coupling. This cracking is initiated by fretting that is caused by a small amount of relative motion. Specifically, the locking key in the keyway may move slightly in relation to the rotor shaft and the coupling.
There is a desire therefore for an improved rotor design that would eliminate the fretting and cracking between the locking key and the coupling and the rotor shaft so as to improve fatigue life. The improved design may be a retrofit to existing equipment or the design may be provided in new equipment.